Pressure cooker



Feb. 27, 1940. P, W, STEPHENS 299975 PRESSURE cooxER` Fledauly s, 193e :s snapte-sheet 1 Feb. 27, 1940. y

P. w. STEPHENS wh? PRESSURE comma Filed July 6 195e v 3 Sheets-Sheet 2, Zz' .2,

Feb. 27, 1940. P, w, STEPHENS 2,191,975

PRESSURE coxER Filed July 6. 1956 3 Sheets--Sheetl 3' Patented Feb. 1940 i i UNITED STATES aimais P.arrENT OFFICE" PRESSURE cooKEn Percy W. Stephens, Chicago, lll. Application July 6, 193s, seriaiNo. 89,189'

12 Claims.

This invention relates to pressure cookers, and` i more particularly to improved closure means therefor.

One feature of this invention is that it provides a One-piece positively operated closure band for sealing the cover Ato the body portion of the cooker; another feature of this invention is that the closure means and safety valve rneans are so constructed and arranged that the cover cannot l0 be removed from the cooker without first venting the pressure therein; a further feature of this invention is that the relief valve is so constructed that venting of over pressure inthe cooker` does not throw the valve out of its operative range; other features and advantages of this invention will be apparent from the following specieY .Y

cation and the drawings, in which- Fig. 1 is a plan view of the cooker with the closure band in position therein; Fig. 2I is'a side elevation of the cooker shown in Fig. 1; Fig. 3 is a fragmentary sectional View along the line 3-3 of Fig. 1; Fig. 4 is a detailed sectional view of the valvelarrangement along the line 4-4 of Fig. 1; Fig, 5 is a detailed sectional view along the g5 line 5-5 of Fig. 1; Fig. 6 is a plan view of the -clgsure band in expanded position; Fig. 7 is a detailed sectional view of a modified form, similar to Fig. 5; Fig. 8 is a similar view of another modification; and Fig. 9 is a similar view of -still anw other modification wherein no sealing gasket is employed.

In order to make an operative pressure cooker some means must be provided for clamping the cover to the body portion of the cooker to eiect a seal therebetween sufficient to maintain the desired pressure i'n the cooker. This invention provides a closure or clamping means with positive operating means for clamping or disengaging it, the whole so arranged that a single movement effects a tight seal all the way' around the periphery of the cover. A relief valve is pi'iricled4 in the cover togprotect against' excessive pressures within the cooker, and interlocking means is arranged between the positive operating means for the closure and the valve, so that the closure can only be removed'to break the seai around the edge of the cover after the interior of the cooker has been vented to atmosphere through'the valve.

In the particular embodiment of this invention illustrated herewith a pressure cooker is'shown having a body portion'lll and a cover II. 'Ihe cover II has thereon a pressure gauge I2 of standard type', arelief valve I I, and a handle orv knob I4'Qof heat-insulating material. '111e cover Il is provided with a channelled peripheral por- I (Cl. 22o-61) tionV I5 having therein Aan annular gasket I6 adapted to contact the lip or upper edge I1 of the body portion I0 of the cooker.

Closure means I8 is provided for clamping the cover into sealing engagement with the edge I1, l this closure means comprising a flexible metal band I9 having fastened thereto closure segments 2i! having a top flange 2I and a bottom flange 22. It will be notedlthat the topvflange 2| diverges downward from the plane of the band at 1 a sl-ght angle, here shown as about five degrees; the bottom flange 22 diverges substantially from the plane of the band, being here shown at an angle of about forty-five degrees with such plane. It will. be noted, referring more particularly to l Figaro, that the edge of the body portion is rolled back on itself, as by a curling die, to provide a substantially Irigid annularA or peripheral roll 45 adapted to be engaged by the'angularly disposed surface of the bottom flange 22. i

The ends ofthe exible band I9 are adapted to be drawn together or separated by the action of toggle-meanscomprising the base 24 of the operating lever 25 and the spring connecting link 26.v One end of the base 24 of the operating lever is i connected to one end of the flexible band I9, as by the pivot 21; one end of the-spring link 26 is movably connected to the other end of the band I9, as by the pivot 28; and the base 24 of the lever and the link 26 are pivotally connected toi gether at the point 29. Movement of the lever 25 `thus actuates the toggle means to positively vary theeiective diameter of the closure band, either. drawing it together to yclamp the cover on the body portion of the cooker, or expanding the band i to enable it to be conveniently removed from closure relationship with the cooker.

Referring again to Fig. 5, it will be seen that contraction of the band by the toggle means results, through the-interaction of the surface l 45 and the diverging flange 22, to seat the cover firmly on the surface I1. The top flange 2I'is set at a slight downward angle to the plane of the band, as described before, and drawing the band tight tends to further tilt this top flange l downward. Thus the sealing pressure on the cover is effected at a point substantially centrally of the gasket I6, rather'than near the outer edge thereof.

'Ihe cover II has an opening 30 therethrough 4 in which a tube 3| is mounted. Valve means is provided for closing the upper end of this tube 3|, here shown as a valve body 32 having .-a relatively large .chamber 33 in the upper pari thereof'.4 with openings 34' through the top thereof f 36 projects downwardly into the chamber 33 from the top of the valve body 32, and is adapted to close the opening at the top of the tube 3|. The valve body 32 is also provided with a handle 46 of heat insulating material, enabling it to be conveniently removed when the cooker is hot. The internal diameter of the tube 3| and the weight of the valveI body 32 are so proportioned that pressures up to the desired maximum will not lift the valve member 34 from its sealing position in the top of the tube 3|; as soon as .the pressure within the cooker exceeds the desired maximum, however, the upward force exerted on the valve member 34 is su'icient to lift it from its seat'in the top of the tube 3|, thus venting the vapor pressure within the cooker into the chamber 33. Since this chamber is relatively large with respect to th size of the passage through the tube 3| and it has a plurality of relatively large openings 3| in the top thereof communicating to atmosphere, the vapors coming up through the tube yare able to expand in the chamber 33 and pass to atmosphere without' their expansion reaction throwing the valve body up high enough to disturb the operative relationship between the valve member 34 and the tube 3|. Thus, after the pressure has vented itself to a safe point the valve 33 again drops into position, closing the tube 3|.

In the particular embodiment of this invention disclosed herewith, the internal diameter of the tube is 3l-z inch, and the valve weight eight ounces, the relief valve Venting at a pressure of fifteen pounds per square inch. If it is desired to have the pressure relieved at a lower point, a

proportionately larger tube or smaller weightV should be used.

The lever 25 which operates the toggle means is provided with an extension portion 35 having an upturned end or means 36 adapted to engage the valve body 32 when the lever 25 is in closed or clamping position. When the toggle is being either opened or closed the valve member 32 is removed by means of a handle 46. To close the cooker the cover is placed in position, the closure band placed around it in the proper plane, and the lever 25 moved into the position shown in Fig. 14 to draw the ends of the metal band I9 together through the tension of the spring member 26 and thus clamp the cover onto the body portion of the cooker through the Wedging action of the diverging flange 22 on each of the closure segments 20. When the lever is in closed position the valve body 32 is placed over the tube 3|, and the lever 25 is thus locked in that position; that is, it is prevented from outward movement by engagement of the valve member or body 32 with the upward projection 36. Before the closure means can be loosened to remove the cover, therefore, the valve body 32 must be removed to vent any pressure remaining within the cooker' to atmosphere. This is an important safety feature, since it prevents a house- Wife from opening the closure means and breaking the seal between the cover and bodyl portion of the cooker while there is any pressure remaining within the cooker.

Each closure segment 2|) is fastened to the exible band |9'throughout a portion of its length,

here shown as being spot-welded thereto at the two points 31 and 38. This two-spaced-point fastening is effective to maintain the band against the closure segment throughout the distance between the two points, justas though 'it were integrally fastened thereto for that length. Referring more particularly to Fig. 1, it will be seen that when in closed position the `closure segments are mounted rather closely adjacent each other, that is, there is very small spacing between them. This small spacing enables a cover lof relatively thin metal to be used, since it is furnished with support throughout practically its entire circumference. On the other hand, since the segments are not fastened to the flexible band at their ends but somewhat removed therefrom, a fairly large portion of the fiexible band is available for expansion and contraction when the toggle means is used to vary the effective diameter of the band.Y This will be readily seen from the consideration of Fig. 6, where the closure band is shown in expanded position. The length throughout which the segments are fastened to the band is important, since if'they are fastened only in the center they do not move outwardly suciently far for the iianges to clear the edge of the cover when the band is expanded; on the other hand, if they arefastened to the band clear to the ends thereof, the only part of the band available for flexing is the very short distance between them, which makes a very stiff and undesirable closure ring. It has been found that the segment should be effectively attached to the band throughout a space from about one-fifth to three-fifths of the segment length, and preferably the spot welds 3l and 38 have a spacing between them about one-third of the segment length.

A modified construction is shown in Fig.' 7, wherein the body portion of the cooker may be of enameled sheet iron. In this'construction the edge of the body portion is also formed in a small roll 40 at a point removed from the actual body. An enclosing tube or second roll 4| of some corrosion resisting metal, as aluminum, is then rolled into place about the portion 40. This tube 4| provides a bearing surface for the lower flange 22, so that constant action of this flange thereagainst does not damage the corrosion resistance, as would be the case were the ange used directly against the enameled surface of the body.

The modification shown in Fig. 8 is adapted for use where the body portion of the cooker is of metal of sufficient strength torwithstand the pressure. of the closure band at the surface 23 without the necessity of a reinforcing roll. This surface 23 gives a broader contact with the inner. surface of the flange 22, and may be very conveniently formed by a die.

Fig. 9 illustrates a modified construction wherein the gasket IB is eliminated and a metalto-metal seal is formed between the cover`4`| and the body portion'48. T'he body portion is curled outward and downward, as at 49, and is adapted to be contacted near the bottom of the curl by the ange 22 in the usual manner to force the cover 41 into engagement with the body portion of the cooker. The outer edge of the cover, here made of resilient metal, is given 'ammira bodiments of my invention, it is to'be understood that it is capable ofv many modiilcations. Changes,` therefore, in the construction" and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is my intention to claimall novelty inherent in my invention as broadly as permissible, in view of the., prior art. 1

I claim:

1. A closure device for sealing the cover to the body portion ofa pressure cooker, including: a substantially circular flexible metal band; closure segments fastened to said band and having flanges extending inwardly therefrom, the

top flange of each of said segments diverging slightly downward from the lplane of said band and the bottom ange diverging substantially downward therefrom; and means fox` positively varying the effective diameter of said band.

2. Apparatus of the character claimed in claim 1 wherein said band has at least three segments fastened thereto.

3. A closure device for sealing the cover to thel body portion of a pressure cooker, including: a substantially circular flexible metal band; at least three closure segments fastened to said band closely adjacent each other and having fflanges extending inwardly therefrom, at least one of said anges on each of said segments dil one-fifth to tl'xree-iifths of the length of the segment.

5. Apparatus of the character claimed in claim'- 3, wherein said points are spaced apart substantially one-third of the length of the segment and symmetrically located with respect to the ends of the segment.

6. A closure device for sealing a cover having a valvel projecting thereabove to the body portion of 'a pressure cooker, including: means for .adapted .clamping saidcover against said body portion;

lever means for operating said clamping means; and means on said lever adapted to be lockably engaged by said' valve. whereby said clamping means cannot be released until said valve has been opened.

'7. A pressure cooker o f the character de-` scribed, including: a body portion; a cover; valve means in said cover; means for clamping said -cover against said body portion to eifect a seal therebetween: lever means for operating said clamping means; and means on said lever to interlock with said Valve when said lever is in clamped position and said valve is in closed position, whereby said valve must be opened to disengage said last-mentioned means.

8. A pressure cooker of the character de-1v scribed, including: a body portion; acover; valve means in said cover projecting thereabove; 'a closure band; toggle means -for varying the effective diameter of said band to clamp said cover against said body portion to eect a seal therebetween; `lever means for operating said toggle means; and means on said lever adapted to be lockingly engagedby said valve means when said lever is in clamped position -and said valve is closed, whereby said valve must be opened to disengage said lever.

9. A pressure cooker of the character described, including: a body portion; va cover having an opening therethrough; valve means adapted to close said opening; a closure band substantially circular inshape; closure segments on said band. having inwardly projecting anges, at least one of the anges in each of said segments diverging substantially from the plane of the band; toggle means for varying the effective diameter of. said band to clamp said cover against said body portion to effect a seal therebetween; lever means for operating said toggle means; and projecting means on said lever adapted to be lockingly engaged by a flange on said valve means to retain said lever in clamped position when said valve is. closed', whereby said valve must be opened to release said closure means,

10. A container of the character described, including: a body portion having an outwardly and downwardly turned peripheral curl at the top thereof; a peripheral` roll at the edge of said curl; a cover adapted to form,a` closure for said container; and a closure band having inwardly extending'iianges, at least onev of said'flanges ldiverging from the plane of said band, one of said flanges being adapted to contact said cover and thev other said roll, whereby contraction of said band seals said cover to said body portion.

11. Apparatus of the character claimed in claim 10, wherein a second roll of metal is interposed between the roll and the flange.

12. A retaining device comprising expansible and contractible retaining means having porconnected therewith intermediate said parts I thereof.

- 'PERCYW.S.U 

